a/c runs

I bought a house almost 2 years ago. My a/c is the original from 1996. I know...the time to change the unit is coming. Anyways, the a/c runs constantly. If I set the thermostat to 76, the coldest it will get is 78 (according to the thermostat) and never stops running. I live in Phoenix so it's hot as Hades but I honestly don't remember if we had this problem last year or not.

I looked on youtube and searched these forums and I think everything is clean and in good shape. Is it that I could need something as simple as a recharge? I'm sure it could be something much more extensive, but considering everything 'looks' good, this is what I'm guessing.

Does anyone know how to recharge a unit or if it's even legal for a homeowner to do it?

lol. A rule I've always followed is "never break more than one law at a time"

I don't mind buying the tools if I can use them again because I'm a tool whore. The problem is that due to my unit using HCFC-22 which is an outdated refrigerant from what I've read. I guess I will have to call the pro in